JP7241276B2 - street lighting fixture - Google Patents

Description

The present disclosure relates to street lighting fixtures.

Lighting fixtures used for street lighting are required to improve the visibility of pedestrians, bicycles, steps, and visible objects passing through the street, and to ensure safety in terms of traffic and crime prevention. By the way, human luminosity differs between photopic vision, scotopic vision, and mesopic vision. In photopic vision (in a bright environment), color perception is possible due to the action of cone cells. In scotopic vision (in a dark environment), color perception is not possible because cone cells do not function, but luminosity is improved by the action of rod cells.

Mesopic vision (in a dim environment) is a state intermediate between photopic vision and scotopic vision, and both cone cells and rod cells function. It is said that the brightness at which human mesopic vision occurs is about 0.01 to 10 lx, and it is said that when the brightness is higher than this, it is photopic, and when the brightness is lower than this, it is scotopic. .

Here, in a dark environment, the peak of luminosity shifts to the short wavelength side with respect to a bright environment. Such a phenomenon is well known as the Purkinje phenomenon. In addition, cone cells are abundant in the central side of the retina, and the number decreases significantly away from the center, whereas rod cells do not exist in the central side of the retina and decrease in number away from the center. increase sharply. Therefore, in mesopic vision, a pedestrian walking on a street often visually recognizes, for example, the face of an opposite person with central vision, and also visually recognizes objects on the side of the street with peripheral vision. As a lighting fixture using the Purkinje phenomenon, for example, there is an outdoor lighting fixture disclosed in Patent Document 1.

JP 2008-091232 A

2. Description of the Related Art Conventionally, as an example of a lighting device using the above-described Purkinje phenomenon, there is an outdoor lighting device. Here, as the correlated color temperature increases, the S/P, which is the visibility evaluation index under the mesopic environment, tends to increase. It improves the visibility of pedestrians. The S/P ratio is a numerical value for evaluating the visibility of light, and the higher the S/P ratio, the higher the visibility under the mesopic environment.

Conventional lighting fixtures focus on visibility of pedestrians, but in outdoor walking spaces, it is necessary to achieve both good visibility of the space and visibility of opposing pedestrians and the good atmosphere of the space. is important. However, in order to improve visibility, a high S/P ratio is preferable, and therefore a high correlated color temperature is suitable. , it is difficult to achieve both visibility and good atmosphere.

Accordingly, the present disclosure provides a street lighting fixture that enhances visibility and improves the atmosphere of a space in a mesopic environment.

A street light according to an aspect of the present disclosure is arranged at a height of 2 m or more and 5 m or less from a road surface, and includes a light emitting unit that irradiates the street with white light, and the white light has a correlated color temperature of 5000 K or more and 6500 K. or less, the color deviation is −10 or more and +10 or less, the S/P ratio, which is the ratio of the luminous flux in scotopic vision and the luminous flux in photopic vision, is 2.0 or more, and the city illuminated with the white light The average horizontal illuminance on the illuminated surface on the road is 1 lx or more.

According to the street lighting fixture of the present disclosure, in a mesopic environment, when viewed from pedestrians passing through the street, the visibility of opposing pedestrians, bicycles, steps, visible objects, etc. is improved, and the atmosphere is enhanced. can do better.

FIG. 1 is a schematic diagram showing a light irradiation surface of a street lighting fixture according to an embodiment. FIG. 2 is an external perspective view of the street lighting fixture according to the embodiment. FIG. 3 is a plan view showing the internal configuration of the street lighting fixture according to the embodiment. FIG. 4 is an external perspective view showing the illumination light source according to the embodiment. FIG. 5 is a schematic cross-sectional view of the illumination light source taken along line VV in FIG. FIG. 6 is a diagram showing the emission spectrum of the street lighting fixture according to the example. 7 is a diagram showing an emission spectrum of an illumination light source according to Comparative Example 1. FIG. 8A and 8B are a plan view and a side view of a comparative verification experiment space for illumination light sources according to Example, Comparative Example 1, and Comparative Example 2. FIG. FIG. 9A is a diagram showing the results of a comparative verification experiment of visibility in the illumination light sources according to Example, Comparative Example 1, and Comparative Example 2. FIG. FIG. 9B is a diagram showing the results of a comparative verification experiment of the atmosphere of the space in the illumination light sources according to Example, Comparative Example 1, and Comparative Example 2; FIG. 10 is an external perspective view showing an illumination light source according to another embodiment. 11 is a schematic cross-sectional view of the illumination light source taken along line XI-XI in FIG. 10. FIG.

(Embodiment)
Hereinafter, street lighting fixtures according to embodiments will be described with reference to the drawings. It should be noted that the embodiments described below are all comprehensive or specific examples. Numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, connection forms, and the like shown in the following embodiments are examples, and are not intended to limit the present disclosure. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in independent claims representing the highest concept will be described as arbitrary constituent elements.

Each figure is a schematic diagram and is not necessarily strictly illustrated. Moreover, in each figure, the same code|symbol is attached|subjected to substantially the same structure, and the overlapping description may be abbreviate|omitted or simplified.

In addition, in the following embodiments, expressions using "substantially" such as a substantially semicircular shape are used. For example, a substantially semicircular shape means not only a perfect semicircular shape, but also a substantially semicircular shape, that is, including a difference of about several percent, for example. The same applies to cases where expressions using other "abbreviations" are described.

[Structure of Street Lighting Equipment]
First, a street lighting fixture according to an embodiment will be described. FIG. 1 is a schematic diagram showing a light irradiation surface of a street lighting fixture according to an embodiment. As shown in FIG. 1, a street lighting fixture 100 is installed to irradiate a street 200 with light. The street lighting fixture 100 is supported above the street 200 by the columnar member 110 . The street lighting fixture 100 is used, for example, in a living street. As shown in FIG. 1, a plurality of street lighting fixtures 100 are installed along a street 200 at predetermined intervals.

Moreover, the street lighting fixture 100 irradiates the road surface of the street 200 with light. The street lighting fixture 100 illuminates an irradiation surface LA (a hatched area of the street 200 in FIG. 1) of the road surface.

The street lighting fixture 100 includes an illumination light source 310, which will be described later, to irradiate light that enhances visibility in a mesopic environment. The street lighting fixture 100 is installed at a height of 2 m or more and 5 m or less from the road surface of the street 200, and is set so that the average horizontal plane illuminance of the irradiation surface LA is 1 lx or more. Here, the average horizontal plane illuminance is the illuminance per unit area of light irradiated on a horizontal plane. In this specification, the average horizontal surface illuminance indicates the average illuminance of the illumination surface LA that the street lighting device 100 illuminates the road surface of the street 200 .

The spread angle of the light emitted from the street lighting fixture 100 is not particularly limited as long as the street 200 is illuminated so that the average horizontal plane illuminance is 1 lx or more. The street lighting fixture 100 may be designed so that the street 200 is efficiently illuminated.

In addition, the white light emitted from the street lighting fixture 100 is irradiated toward the street 200 side (lower side) using a housing 120 (see FIG. 3), which will be described later, and reflectors and lenses (not shown). there is This is because, for example, when the street lighting device 100 emits white light at night, if the street lighting device 100 irradiates the light above the street lighting device 100, the night sky is illuminated with the light, which deteriorates the landscape and the surrounding animals and plants. This is because there is a risk of causing light pollution such as adversely affecting the environment. Therefore, most of the white light emitted from the street lighting fixture 100 is preferably irradiated to the lower side of the street lighting fixture 100 . For example, the white light emitted upward from the street lighting fixture 100 is set to 5% or less of the total luminous flux of the white light. Note that "upward" or "downward" from the street lighting fixture 100 means, for example, that the angle of light emitted from the street lighting fixture 100 is tilted upward or downward with respect to the horizontal direction. means whether or not

In addition, the amount of white light emitted by the street lighting fixture 100 is set to be small in the horizontal direction and upward direction. This is because a lighting fixture with a wide light distribution angle may cause pedestrians on the street 200 to perceive white light emitted by the lighting fixture as glare. In this way, in order to prevent pedestrians on the street from perceiving the white light as glare, for example, the luminance value of the white light emitted by the street lighting fixture 100 at a vertical angle of 85 degrees or more is 20000 cd/m ² or less. is set to In order to achieve the luminance value at the vertical angle, the street lighting fixture 100 uses a housing 120 (see FIG. 3), which will be described later, a reflector plate and a lens (not shown), etc., so that the luminance value at the vertical angle of 85 degrees or more is It is configured to be 20000 cd/m ² or less.

A detailed configuration of the street lighting fixture 100 will be described below.

FIG. 2 is an external perspective view of the street lighting fixture 100 according to the embodiment. FIG. 2 is an external perspective view of the street lighting device 100 installed on the street 200 and viewed from below. FIG. 3 is a plan view showing the internal configuration of the street lighting fixture 100 according to the embodiment when the translucent cover 130 is removed and viewed. As shown in FIGS. 2 and 3 , the street lighting fixture 100 includes a housing 120 , a translucent cover 130 and a light emitting section 300 .

The housing 120 accommodates the light emitting unit 300 and holds the translucent cover 130 that covers the accommodated light emitting unit 300 . The housing 120 is formed using, for example, a metal material, but may be formed using other materials such as a resin material. In addition, the inner surface of the housing 120 may be made of a light reflecting material in order to increase the efficiency of light utilization.

The translucent cover 130 is a cover member that transmits light from the light emitting section 300 and is attached to the housing 120 . The translucent cover 130 can be made of, for example, a glass material or a transparent resin material such as acrylic or polycarbonate. Note that the translucent cover 130 may have light diffusing properties. Note that the street lighting fixture 100 may not include the translucent cover 130 .

Also, the light emitting unit 300 includes an optical lens 150 .

The optical lens 150 is a lens member for controlling light distribution of light emitted from the illumination light source 310 . For example, a plurality of optical lenses 150 are arranged so as to cover each of the plurality of illumination light sources 310 included in the light emitting unit 300 as shown in FIG. As a material of the optical member 150, for example, a transparent resin material such as acrylic resin is adopted.

The light emitting unit 300 emits white light toward the street 200 . Specifically, the light emitting unit 300 includes a plurality of illumination light sources 310 arranged in two rows in the longitudinal direction of the street lighting fixture 100 . As will be described later, the illumination light source 310 includes, for example, a light-emitting element and a phosphor that converts the wavelength of part of the light emitted from the light-emitting element. In addition, the light emitting section 300 may include at least one illumination light source 310, and the number of the illumination light sources 310 arranged is not limited.

The street lighting fixture 100 may also include a power supply unit 140 that supplies the lighting light source 310 with electric power for lighting the street lighting fixture 100 . The power supply unit 140 includes, for example, a power supply circuit that converts AC power from a commercial power supply into DC power and outputs the DC power to the illumination light source 310 . The power supply unit 140 may be built in the street lighting fixture 100 or may be installed separately from the street lighting fixture 100 .

[Structure of Light Source for Illumination]
Next, the configuration of the illumination light source 310 according to the embodiment will be described with reference to the drawings.

FIG. 4 is an external perspective view of the illumination light source 310 according to the embodiment. FIG. 5 is a schematic cross-sectional view of the illumination light source 310 along line VV in FIG.

As shown in FIGS. 4 and 5, the illumination light source 310 according to the embodiment is implemented as an SMD (Surface Mount Device) type light emitting device. The illumination light source 310 can emit white light that is perceived as bright in central vision and peripheral vision in a mesopic environment, as described below. For this reason, the illumination light source 310 is suitable for a street lighting fixture used in a dark environment such as at night.

The illumination light source 310 includes a container 311 having a recess, a sealing member 312 enclosed in the recess, and an LED (Light Emitting Diode) chip (light emitting element) 313 mounted in the recess.

A container 311 is a container that accommodates an LED chip 313 and a sealing member 312 . The container 311 also includes an electrode 314 that is a metal wiring for supplying power to the LED chip 313 . LED chip 313 and electrode 314 are electrically connected by bonding wire 315 . The material of the container 311 is metal, ceramic, or resin, for example.

Aluminum oxide (alumina), aluminum nitride, or the like is used as the ceramic. Moreover, as the metal, for example, an aluminum alloy, an iron alloy, a copper alloy, or the like having an insulating film formed on the surface is adopted. As the resin, for example, glass epoxy made of glass fiber and epoxy resin is used. Note that the container 311 may be made of a combination of the materials described above.

Note that, for the container 311, for example, a material having a relatively high light reflectance (for example, a light reflectance of 90% or more) may be employed. By adopting a material having a relatively high light reflectance for the container 311 , the light emitted from the LED chip 313 can be reflected on the surface of the container 311 . As a result, the light extraction efficiency of the illumination light source 310 is improved. Further, the inner surface of the container 311 in which the LED chip 313 is arranged may be processed so as to increase the light reflectance.

The LED chip 313 is an example of a light-emitting element, and is a blue LED chip that emits blue light. The LED chip 313 is, for example, a gallium nitride-based LED chip made of an InGaN-based (indium-gallium-nitride-based) material and having a central wavelength (emission peak wavelength of an emission spectrum) of 430 nm or more and 460 nm or less.

The sealing member 312 is a sealing member that seals at least part of the LED chip 313 , bonding wires 315 and electrodes 314 . Also, the sealing member 312 contains a wavelength conversion material that converts the wavelength of part of the light emitted from the LED chip 313 . Specifically, the sealing member 312 is made of a translucent resin material containing a plurality of green phosphors 317a and a plurality of red phosphors 317b as wavelength conversion materials. Although the translucent resin material is not particularly limited, for example, methyl-based silicone resin, epoxy resin, urea resin, or the like may be used.

The green phosphor 317 a is an example of phosphor (phosphor particles), and is excited by the blue light from the LED chip 313 to emit green light having a wavelength different from that of the blue light from the LED chip 313 . Specifically, the green phosphor 317a employs a Lu ₃ Al ₅ O ₁₂ :Ce ³⁺ phosphor having a center wavelength of light of 540 nm or more and 550 nm or less.

As will be described later, in the illumination light source 310, the S/P ratio of the white light emitted by the illumination light source 310 is increased. The S/P ratio is an evaluation index of visibility under a mesopic environment. The higher the S/P ratio, the higher the visibility of the light under the mesopic environment. Here, in order to increase the S/P ratio, it is effective to increase the light component in the blue-green region with a wavelength of 480 nm or more and 520 nm or less. Lu ₃ Al ₅ O ₁₂ :Ce ³⁺ phosphor is effective in increasing the light component in the blue-green region from the viewpoint of high wavelength conversion efficiency.

And when the Lu ₃ Al ₅ O ₁₂ :Ce ³⁺ phosphor is employed, the wavelength conversion efficiency decreases if the central wavelength of light is smaller than 540 nm. On the other hand, if the center wavelength of light is longer than 550 nm, the effect of increasing the light component in the blue-green region, that is, the effect of increasing the S/P ratio is reduced. Therefore, in the embodiment, a Lu ₃ Al ₅ O ₁₂ :Ce ³⁺ phosphor having a center wavelength of light of 540 nm or more and 550 nm or less is employed.

Any phosphor may be employed as the green phosphor 317a as long as the emission spectrum, which will be described later, can be achieved, as long as the reduction in light conversion efficiency is acceptable. For example, an yttrium-aluminum-garnet (YAG)-based phosphor may be employed as the green phosphor 317a. Further, for example, a halosilicate-based phosphor may be employed as the green phosphor 317a. Further, for example, an oxynitride-based phosphor may be employed as the green phosphor 317a.

The red phosphor 317 b is an example of a phosphor, and is excited by the light from the LED chip 313 to emit red light having a wavelength different from that of the blue light from the LED chip 313 . Specifically, a (Sr, Ca)AlSiN ₃ :Eu ²⁺ phosphor having a center wavelength of light of 610 nm or more and 620 nm or less is employed for the red phosphor 317b. Note that any phosphor may be employed for the red phosphor 317b as long as the emission spectrum described later can be realized.

With the configuration described above, part of the blue light emitted by the LED chip 313 is wavelength-converted into green light by the green phosphor 317 a contained in the sealing member 312 . Similarly, another part of the blue light emitted by the LED chip 313 is wavelength-converted into red light by the red phosphor 317b included in the sealing member 312. FIG. The blue light not absorbed by the green phosphor 317a and the red phosphor 317b, the green light wavelength-converted by the green phosphor 317a, and the red light wavelength-converted by the red phosphor 317b are combined into a sealing member. Diffuse and mix in 312 . White light is thereby emitted from the sealing member 312 . That is, the illumination light source 310 emits white light by mixing the light from the LED chip 313 with the light emitted from the green phosphor 317a and the red phosphor 317b.

Examples and Comparative Example 1 of the emission spectrum of the white light emitted by the illumination light source 310 will be described below.

[Example]
FIG. 6 is a diagram showing the emission spectrum of the illumination light source 310 according to the example. The vertical axis of FIG. 6 is normalized with the intensity of light having a wavelength of 450 nm in the emission spectrum being 1.0.

The illumination light source 310 according to the embodiment includes an LED chip 313 having an emission peak at a wavelength of 450 nm, a green phosphor 317a (Lu ₃ Al ₅ O ₁₂ :Ce ³⁺ phosphor) having an emission peak at a wavelength of 545 nm, and a wavelength of 615 nm. and a red phosphor 317b ((Sr, Ca)AlSiN ₃ :Eu ²⁺ phosphor) having an emission peak at . In the illumination light source 310 according to the embodiment, the mixed amount of the green phosphor 317a and the red phosphor 317b is adjusted so that the correlated color temperature of the white light emitted from the illumination light source 310 is 5500K. . That is, the correlated color temperature of the white light emitted by the illumination light source 310 according to the example is 5500K.

As shown in FIG. 6, the ratio of the light intensity at a wavelength of 510 nm to the light intensity at the first peak (wavelength of 450 nm) of the emission spectrum is 0.47. The ratio of the light intensity at a wavelength of 580 nm (a1 in FIG. 6) to the light intensity at the first peak of the emission spectrum is 0.60. Also, the ratio (b1/a1 in FIG. 6) of the light intensity at a wavelength of 650 nm (b1 in FIG. 6) to the light intensity at a wavelength of 580 nm is 0.45. Also, the emission spectrum of the illumination light source 310 according to the example has a second peak at a wavelength of 580 nm. In addition, the second peak means a portion where the light intensity is the second highest after the emission peak (first peak) at a wavelength of 450 nm. Also, the color deviation (Duv) of the illumination light source 310 according to the example is −0.80. Here, the color deviation is the deviation from the color temperature on the black body locus.

In addition, the general color rendering index (Ra) of white light emitted by the illumination light source 310 according to the example is 80. The S/P ratio, which is the ratio of the luminous flux in scotopic vision and the luminous flux in photopic vision, of white light emitted by the illumination light source 310 according to the embodiment is 2.0.

The S/P ratio is an evaluation index of visibility under a mesopic environment. The higher the S/P ratio, the higher the visibility of the light under the mesopic environment. The S/P ratio (R _SP ) is, for example, when V(λ) is the spectral luminous efficiency in photopic vision of the illumination light source 310 and V′(λ) is the spectral luminous efficiency in scotopic vision, It can be calculated based on the following formula (1).

In formula (1), K is the maximum photopic luminosity (= 683 lm/W), K' is the maximum scotopic luminosity (= 1699 lm/W), and Φ _e (λ). is the spectral total radiant flux of the illumination light source 310 .

[Comparative Example 1]
7 is a diagram showing an emission spectrum of an illumination light source according to Comparative Example 1. FIG.

The illumination light source according to Comparative Example 1 has the same overall configuration as the illumination light source 310, but differs in the phosphor contained in the sealing member. Specifically, the illumination light source according to Comparative Example 1 includes an LED chip having an emission peak at a wavelength of 450 nm and a green phosphor (Y ₃ Al ₅ O ₁₂ :Ce ³⁺ phosphor) having an emission peak at a wavelength of 555 nm. Prepare. The illumination light source according to Comparative Example 1 does not include a red phosphor. In the illumination light source according to Comparative Example 1, the mixed amount of the green phosphor is adjusted so that the correlated color temperature of the white light emitted from the illumination light source is 5000K. That is, the correlated color temperature of the white light emitted by the illumination light source according to Comparative Example 1 is 5000K.

As shown in FIG. 7, the ratio of the light intensity at a wavelength of 510 nm to the light intensity at the emission peak (wavelength of 450 nm) of the emission spectrum is 0.27. The ratio of the light intensity at a wavelength of 580 nm (A1 in FIG. 7) to the light intensity at the emission peak of the emission spectrum is 0.66. Also, the ratio (B1/A1 in FIG. 7) of the light intensity at a wavelength of 650 nm (B1 in FIG. 7) to the light intensity at a wavelength of 580 nm is 0.40.

In addition, the general color rendering index of white light emitted from the illumination light source according to Comparative Example 1 is 70. The S/P ratio of white light emitted from the illumination light source according to Comparative Example 1 is 1.7.

[Impression evaluation]
Next, with reference to FIG. 8, FIG. 9A and FIG. 9B, the verification results of the impression evaluation by the sensory test performed using the illumination light sources of the above example and comparative example 1 will be described. In the sensory test, the illumination light source of Comparative Example 2 that irradiates white light with a correlated color temperature of 8000 K was prepared and compared with the illumination light sources of Example and Comparative Example 1 for verification. The illumination light source of Comparative Example 2 has the same overall configuration as the illumination light source 310, but the green phosphor is added so that the correlated color temperature of the white light emitted from the illumination light source of Comparative Example 2 is 8000 K. and a light source in which the mixed amount of the red phosphor is adjusted. That is, the correlated color temperature of the white light emitted by the illumination light source according to Comparative Example 2 is 8000K. Moreover, the S/P ratio of the white light emitted by the illumination light source according to Comparative Example 2 is 2.0 or more.

8A and 8B are a plan view and a side view for explaining a comparative verification experiment space of illumination light sources according to the example, the first comparative example, and the second comparative example. Specifically, (a) of FIG. 8 is a plan view (top view) for explaining a comparative verification experiment space for the illumination light sources according to Example, Comparative Example 1, and Comparative Example 2, and FIG. (b) is a side view for explaining a comparative verification experiment space of the illumination light sources according to the example and comparative examples 1 and 2. FIG.

As shown in FIG. 8 , in the comparative verification test space, the street lighting fixture 100 was installed at a height of 4.5 m from the road surface of the street 200 . In addition, the subject U was positioned at a position 5.2 m away from the street lighting fixture 100 in the negative Y-axis direction at a vertical angle of 60°. Also, the visual object V was positioned 4.8 m away from the street lighting fixture 100 in the positive direction of the Y axis. Also, the subject U and the visual object V were positioned at a distance of 1.67 m from the street lighting fixture 100 in the negative direction of the X axis.

Note that the visual object V is a life-sized doll (mannequin). In addition, a color chart in which a plurality of different colors conforming to JIS Z 8721 are recorded is arranged on the visual object V. FIG.

Under these conditions, the illumination light source of the street lighting fixture 100 is replaced with the illumination light sources of the example, Comparative Example 1, and Comparative Example 2, and the visual perception recognized by the subject U is The appearance (visibility) of the object V and the atmosphere of the comparative verification experiment space were evaluated. In the comparative verification experiment, experiments were conducted under three conditions of 1 lx, 3 lx, and 7.5 lx for each of the illumination light sources according to Example, Comparative Example 1, and Comparative Example 2.

FIG. 9A is a diagram showing the results of a comparative verification experiment of visibility in the illumination light sources according to Example, Comparative Example 1, and Comparative Example 2. FIG. FIG. 9B is a diagram showing the results of a comparative verification experiment on the goodness of the atmosphere of the space in the illumination light sources according to Example, Comparative Example 1, and Comparative Example 2; Specifically, (a) of FIG. 9A is a case where the illuminance of each illumination light source is set to 1 lx, and (b) of FIG. 9A is a case where the illuminance of each illumination light source is set to 3 lx. , (c) of FIG. 9A shows the case where the illuminance of each illumination light source is set to 7.5 lx. In addition, (a) of FIG. 9B is a case where the illuminance of each illumination light source is set to 1 lx, and (b) of FIG. 9B is a case where the illuminance of each illumination light source is set to 3 lx. (c) is a case where the illuminance of each illumination light source is set to 7.5 lx.

The number of subjects in the comparative experiment is 29. In addition, the results of the comparative experiments were analyzed using Scheffe's pairwise comparison method. Specifically, first, each subject was allowed to confirm the visual object V under an environment in which white light was emitted from the illumination light source according to Example, Comparative Example 1, or Comparative Example 2. Furthermore, each subject was asked to confirm the visual object V under an environment in which white light was emitted from an illumination light source according to Example, Comparative Example 1, or Comparative Example 2, which was different from the illumination light source that was confirmed. The above action was repeated a certain number of times, separated by a certain amount of time. In addition, each subject was asked how the white light from the illumination light source, which was confirmed earlier, compared to the white light from the illumination light source, which was confirmed later, in terms of visibility and the atmosphere of the space. Evaluation was made by relative scores based on a five-level evaluation scale of 2, -1, 0, 1, and 2. In addition, a plus is an evaluation that the subject feels good, and a minus is an evaluation that the subject feels bad. In addition, each subject was asked how to see the shape of the visual object V in the experimental space, how to see different colors (the above-mentioned color chart) arranged on the visual object V, and how to see the white line placed on the floor. The visibility of the direction, plants, and outer walls was evaluated as visibility.

For example, first, the subject U is made to confirm white light emitted at 1 lx from the illumination light source according to the example. Next, the subject U is made to confirm the white light emitted at 1 lx from the illumination light source according to Comparative Example 1. FIG. Next, the subject U was asked whether the white light of the illumination light source according to the example had better visibility and the atmosphere of the space than the white light of the illumination light source according to the comparative example 1. get evaluated. In this way, the subject first confirms the visual object V under the white light environment illuminated by the target illumination light source, and then confirms the visual object V under the white light environment illuminated by the illumination light source to be compared. Confirm the visual object V. Furthermore, the subjects were asked how they felt the white light emitted by the illumination light source to be compared with the white light emitted by the illumination light source to be compared. The evaluation was made from the two viewpoints of quality) and the goodness of the atmosphere of the comparative verification experiment space. In this way, each subject was given an impression received from white light from three illumination light sources (Example, Comparative Example 1, Comparative Example 2) under conditions of three illuminances (1 lx, 3 lx, 7.5 lx) A comparative evaluation was carried out.

The average degree of preference indicated on the vertical axis of the graphs shown in FIGS. 9A and 9B is the preference for each condition in the paired comparison expressed as a value in the same dimension, and indicates the average degree of preference. . Also, the significant difference shown in FIGS. 9A and 9B is a value calculated by analysis of variance from the evaluation value of each subject. When the scores of the two evaluation objects are separated by this value or more, it is determined that there is a superiority difference. For example, in (a) of FIG. 9A , the difference in score between Example and Comparative Example 2 is 0.03, which is less than the significant difference of 0.29, so there is no significant difference. On the other hand, the difference in score between Example and Comparative Example 1 is 0.61, which is 0.29 or more, so it can be determined that there is a superiority difference.

As shown in (a) and (c) of FIG. 9A , with the illumination light source 310 according to Example, an average degree of preference equivalent to that of the illumination light source according to Comparative Example 2 was obtained. In addition, as shown in (b) of FIG. 9A , with the illumination light source 310 according to Example, a higher average degree of preference than with the illumination light source according to Comparative Example 2 was obtained. These results mean that each subject felt that the illumination light source 310 according to Example and the illumination light source according to Comparative Example 2 provided the same or better visibility. In other words, each subject felt that the higher the S/P ratio, the higher the visibility (better the visibility), even if the correlated color temperatures were close to each other.

Further, as shown in (a), (b), and (c) of FIG. 9B , the illumination light source 310 according to Example obtained an average degree of preference equivalent to that of the illumination light source according to Comparative Example 1. These results show that the white light from the illumination light source 310 according to Example and the white light from the illumination light source according to Comparative Example 1 have different S/P ratios, but the correlated color temperature is 5500 K or 5000 K. , means that the atmosphere of the same space was obtained.

In addition, as shown in (b) and (c) of FIG. 9B , with the illumination light source 310 according to Example, an average degree of preference higher than that with the illumination light source according to Comparative Example 2 was obtained. These results mean that each subject felt the atmosphere of the space with the illumination light source 310 according to Example better than with the illumination light source according to Comparative Example 2. In other words, even if the S/P ratio is 2.0 or more, each subject feels that the atmosphere of the space is better when the correlated color temperature is 5500K.

[Effects, etc.]
Next, the effect obtained by the illumination light source 310 according to the example will be described in comparison with the illumination light sources according to Comparative Examples 1 and 2. FIG.

The emission spectrum of the white light emitted by the illumination light source 310 according to the embodiment has an emission peak in a wavelength range of 430 nm or more and 460 nm or less. In addition, in the emission spectrum of the white light emitted by the illumination light source 310 according to the example, the ratio of the light intensity at a wavelength of 510 nm to the light intensity at the emission peak is 0.45 or more, and the light at a wavelength of 580 nm to the light intensity at the emission peak The strength ratio is 0.60 or more. In the emission spectrum of the white light emitted by the illumination light source 310 according to the example, the ratio of the light intensity at a wavelength of 650 nm to the light intensity at a wavelength of 580 nm is 0.5 or less.

In the illumination light source 310 having an emission spectrum that satisfies such conditions, the light component in the bluish-green region with a wavelength of 480 nm or more and 520 nm or less can be increased, and the S/P ratio of the white light emitted by the illumination light source 310 can be increased. . Specifically, the S/P ratio of the white light emitted by the illumination light source 310 can be 2.0 or higher. The S/P ratio is improved by shifting the emission peak wavelength of the LED chip 313 to the long wavelength side. However, the luminous efficiency of the LED chip 313 decreases when the luminous peak wavelength of the LED chip 313 is shifted to the longer wavelength side. Therefore, the emission peak wavelength of the LED chip 313 is preferably 430 nm or more and 460 nm or less. Furthermore, the emission peak wavelength of the LED chip 313 is more preferably 450 nm or more and 460 nm or less.

Here, in a photopic environment, cone cells having a spectral luminous efficiency peak at a wavelength of 555 nm among visual cells are stimulated. Further, in a mesopic environment such as a road (street) space at night, in addition to cone cells, rod cells having a spectral luminous efficiency peak at a wavelength of 507 nm are stimulated. Since both cone cells and rod cells are stimulated under a mesopic environment, the light component in the blue-green region with a wavelength of 480 nm or more and 520 nm or less in the emission spectrum is increased, so that the illumination light source 310 emits light. The S/P ratio of white light is enhanced.

It should be noted that the S/P ratio is preferably 2.0 or more. Light with an S/P ratio of 2.0 or more is perceived as bright, especially in peripheral vision. Peripheral vision means viewing the peripheral portion of the visual field with a visual angle of 10 degrees or more, for example, and the main activity environment is mesopic vision or scotopic vision. Thus, the illumination light source 310 can emit white light that is perceived as bright under mesopic environments, especially in peripheral vision.

On the other hand, for example, the emission spectrum of the illumination light source according to Comparative Example 1 does not satisfy the condition that the S/P ratio is 2.0 or more. The illumination light source according to Comparative Example 1 has poor visibility under the mesopic environment.

In addition, the illumination light source 310 having an emission spectrum that satisfies the above conditions can emit white light that is perceived bright even in central vision under a mesopic environment due to the shape of the emission spectrum. Note that central vision means viewing the central portion of the visual field with a visual angle of, for example, about 2 degrees or more and less than 10 degrees, and the photopic environment is the main activity environment.

In addition, the white light emitted by the illumination light source 310 according to the embodiment has a general color rendering index of 80 or more, and therefore has high color reproducibility. Therefore, the illumination light source 310 according to the embodiment can more accurately color the color information of the objects installed on the street 200 or around the street 200 . Therefore, misperception of colors by pedestrians on the street 200 is reduced.

On the other hand, for example, the white light emitted by the illumination light source according to Comparative Example 1 has a general color rendering index of 71, and thus has low color reproducibility. Therefore, pedestrians on street 200 may misidentify colors. Therefore, as shown in FIG. 9A , each subject felt that the visibility of the illumination light source 310 of Example and the illumination light source of Comparative Example 2 was equal to or better than that of the illumination light source of Comparative Example 2. It is inferred that the user felt better visibility than the illumination light source of Comparative Example 1.

Further, the correlated color temperature of the white light emitted by the illumination light source 310 according to the embodiment is 5000K or more and 6500K or less. As a result, the illumination light source 310 according to the embodiment can clearly see the white lines on the street 200 and emit natural daylight white (daylight color) light with little bluish tint.

On the other hand, the correlated color temperature of the white light emitted by the illumination light source according to Comparative Example 2 is 8000 K, which is slightly bluish compared to the illumination light source 310 according to the example. Therefore, as shown in FIG. 9B, it is inferred that the subject U felt that the illumination light source 310 of Example provided a better atmosphere in the space than the illumination light source according to Comparative Example 2 did.

As described above, according to the illumination light source 310 of the embodiment, it is possible to achieve both good visibility of the space on the street 200 and good atmosphere of the space. Note that the above characteristics and the above effects may be achieved as light emitted from the street lighting equipment 100, and each of the plurality of illumination light sources 310 installed in the street lighting equipment 100 achieves the above characteristics and the above effects. You don't have to. For example, the street lighting fixture may include a blue LED chip that emits blue light in the light-emitting portion, and may include a green phosphor and a red phosphor in the translucent cover. By doing so, for example, the emission spectrum emitted from the street lighting fixture may be configured to have the emission spectrum shown in the above embodiment.

Further, the correlated color temperature of white light is more preferably 5200K or more and 6000K or less. By doing so, the light component in the blue region (for example, wavelengths of 400 nm to 500 nm) in the white light is further reduced, so scattering of the illumination light is suppressed when fog occurs. Therefore, the safety of pedestrians walking on the street is further improved.

Further, the color deviation of the illumination light source 310 according to the example is −10.0 or more and +10.0 or less. As a result, the illumination light source 310 according to the embodiment can emit more natural white light without being greenish or reddish. The color deviation is more preferably −5.0 or more and +5.0 or less. By doing this, the white light becomes more natural white, and for example, the white lines on the street 200, the white of the appearances, and the like are more clearly visible.

Also, the lumen equivalent (LE) of the illumination light source 310 according to the example is 300 lm/W or more. Here, the lumen equivalent is an index for evaluating visibility per equal energy of light in photopic vision. In other words, light with a large lumen equivalent is interpreted as light that has high visibility per the same light energy in photopic vision, that is, light that is easily perceived by cone cells. Furthermore, illumination with a large lumen equivalent is interpreted as illumination that is easily perceived by cone cells even in mesopic vision. The lumen equivalent is, for example, K is the maximum photopic luminous efficiency (=683 lm/W), V(λ) is the spectral luminous efficiency in photopic vision, and Φ _e (λ) is the total spectrum of the illumination light source 310. In the case of radiant flux, it can be calculated based on the following equation (2).

As a result, the light emitted from the illumination light source 310 has a large percentage of light that is easily perceived by cone cells even in mesopic vision. For this reason, the light emitted from the illumination light source 310 is perceived as bright by pedestrians on the street in mesopic vision in central vision and peripheral vision, so that light energy is used efficiently.

[summary]
Street lighting fixture 100 according to Embodiment 1 includes light emitting unit 300 that is arranged at a height of 2 m or more and 5 m or less from the road surface of street 200 and that irradiates street 200 with white light. The white light has a correlated color temperature of 5000 K or more and 6500 K or less, a color deviation of −10 or more and +10 or less, and an S/P ratio, which is the ratio of the luminous flux in scotopic vision and the luminous flux in photopic vision, of 2.0. That's it. In addition, the average horizontal illuminance on the irradiation surface LA on the street 200 irradiated with white light is 1 lx or more.

As a result, a pedestrian on the street 200 illuminated by the white light emitted from the street lighting fixture 100 is illuminated by white light that is perceived brightly in the peripheral vision. Visibility to exhibits etc. is improved. Therefore, according to the street lighting fixture 100, the safety of pedestrians walking is enhanced.

The white light emitted by the street lighting fixture 100 has a correlated color temperature of 5000 K or more and 6500 K or less and a color deviation of −10 or more and +10 or less. Therefore, the atmosphere of the space irradiated with the white light is favorable. If the space has a good atmosphere, it is expected that the pedestrians on the street 200 will feel more secure.

As described above, according to the street lighting fixture 100, in a mesopic environment, the visibility of pedestrians passing through the street 200, opposing pedestrians, bicycles, steps, visible objects, etc. is improved, and the visibility of the space is improved. atmosphere can be improved. According to the street lighting fixture 100, which can improve the visibility of pedestrians on the street 200 and enhance the sense of security, the pedestrians facing the street can be accurately perceived, and the street due to the bad atmosphere of the space can be improved. Since it is possible to suppress the decrease in the number of 200 pedestrians, it is also expected to be effective as a crime prevention measure.

Further, the white light emitted from the street lighting fixture 100 may have a general color rendering index of 80 or more.

As a result, pedestrians on the street 200 can more accurately recognize colors, and thus can more accurately recognize color information of objects (signs) installed on the street 200 . In addition, the risk of misidentification of the color of the clothes of the opposing pedestrian or the color of the bicycle is reduced.

The emission spectrum of the white light emitted from the street lighting fixture 100 may have a lumen equivalent of 300 lm/W or more and an emission peak in a wavelength range of 430 nm or more and 460 nm or less. Further, in the emission spectrum, the ratio of the light intensity at a wavelength of 510 nm to the light intensity at the emission peak is 0.45 or more, and the ratio of the light intensity at a wavelength of 580 nm to the light intensity at the emission peak may be 0.60 or more. . In the emission spectrum, the ratio of light intensity at a wavelength of 650 nm to light intensity at a wavelength of 580 nm may be 0.5 or less.

As a result, the white light emitted from the street lighting fixture 100 makes pedestrians on the street 200 feel brighter and is white light in which waste of light energy is suppressed.

Moreover, the light-emitting part 300 of the street lighting fixture 100 may include a light source 310 for illumination. The illumination light source 310 may include a light emitting element 313 and a plurality of phosphors that are excited by the light from the light emitting element 313 and emit light with a wavelength different from that of the light from the light emitting element 313 . Further, the light emitting element 313 may have an emission peak in a wavelength range of 430 nm or more and 460 nm or less. That is, the light emitting element 313 employs, for example, an LED chip 313 having a light emission peak in a wavelength range of 430 nm or more and 460 nm or less.

As a result, the illumination light source 310 can emit light that is perceived brightly in both peripheral vision and central vision, and that has improved color reproducibility.

Also, the plurality of phosphors may include a Lu ₃ Al ₅ O ₁₂ :Ce ³⁺ phosphor having an emission peak in a wavelength range of 540 nm or more and 550 nm or less. That is, as the phosphor, for example, a Lu ₃ Al ₅ O ₁₂ :Ce ³⁺ phosphor having high light conversion efficiency in the blue-green region is employed.

As a result, the illumination light source 310 can efficiently emit light that is perceived brightly in both peripheral vision and central vision, and that has improved color reproducibility.

Also, the plurality of phosphors may include (Sr, Ca)AlSiN ₃ :Eu ²⁺ phosphors having an emission peak in a wavelength range of 610 nm or more and 620 nm or less. That is, for the phosphor, for example, a (Sr, Ca)AlSiN ₃ :Eu ²⁺ phosphor having high light conversion efficiency in the red region is adopted.

As a result, the illumination light source 310 can efficiently emit light that is perceived brightly in both peripheral vision and central vision, and that has improved color reproducibility.

Also, the luminous flux of the white light emitted upward from the street lighting fixture 100 may be 5% or less of the total luminous flux of the white light.

According to such a configuration, the white light emitted from the light emitting unit 300 leaks upward from the street lighting fixture 100, thereby reducing the brightness of the night sky and affecting the animals and plants around the street lighting fixture 100, for example. Adverse effects can be suppressed. That is, according to such a configuration, light pollution to the surroundings caused by the street lighting fixture 100 can be suppressed.

Further, the luminance value of white light at a vertical angle of 85 degrees or more may be 20000 cd/m ² or less.

According to such a configuration, pedestrians on the street are prevented from feeling glare from the white light.

(Other embodiments)
Although the street lighting fixture according to the embodiment has been described above, the present disclosure is not limited to the above embodiment.

Although the light source for illumination in which the light emitting element 313 is mounted on the container 311 has been described in the above embodiment, the present invention is not limited to this. Illumination light sources according to other embodiments will be described below. FIG. 10 is an external perspective view showing an illumination light source according to another embodiment. 11 is a schematic cross-sectional view of the illumination light source taken along line XI-XI in FIG. 10. FIG. As shown in FIGS. 10 and 11, the illumination light source 310 a includes a substrate 316 and an LED chip (light emitting element) 313 mounted on the substrate 316 .

The substrate 316 is a substrate having a wiring area provided with the electrodes 314 . The electrode 314 is metal wiring for supplying power to the LED chip 313 . Substrate 316 is, for example, a metal base substrate or a ceramic substrate. Further, the substrate 316 may be a resin substrate using resin as a base material.

Further, as the substrate 316, a substrate having a high light reflectance (for example, a light reflectance of 90% or more) may be employed. By adopting a substrate having a high light reflectance as the substrate 316 , the light emitted from the LED chip 313 can be reflected on the surface of the substrate 316 . As a result, the light extraction efficiency of the illumination light source 310a is improved. As such a substrate, for example, a white ceramic substrate using alumina as a base material is exemplified.

It should be noted that although substrate 316 is rectangular in other embodiments, it may be of other shapes such as circular.

The sealing member 312 is a sealing member that seals at least part of the LED chip 313 , bonding wires 315 and electrodes 314 . Also, the sealing member 312 contains a wavelength conversion material that converts the wavelength of part of the light emitted from the LED chip 313 . Specifically, the sealing member 312 is made of a translucent resin material containing a plurality of green phosphors 317a and a plurality of red phosphors 317b as wavelength conversion materials.

Also, the sealing member 312 of the illumination light source 310a is formed in a dome shape on the substrate 316 so as to have a curvature. Specifically, as shown in FIG. 11, the cross section of the sealing member 312 formed on the substrate 316 is formed to have a substantially semicircular shape. By doing so, the sealing member 312 can collect light emitted from the LED chip 313 and light emitted from the wavelength conversion material sealed in the sealing member 312 . In other words, the sealing member 312 formed to have a curvature functions as a lens that collects the light.

Note that the cross-sectional shape of the sealing member 312 formed on the substrate 316 is not limited. By changing the curvature of the formed sealing member 312, the light emitted from the illumination light source 310a and the street lighting fixture comprising the illumination light source 310a can be changed to a desired irradiation angle. By doing so, the illumination light source 310a and the street lighting fixture including the illumination light source 310a can illuminate the street 200 in a desired irradiation range without newly providing a lens or the like.

In addition, in the above embodiment, the above emission spectrum was realized by two types of phosphors and one LED chip (light emitting element), but such a realization method is only an example, and the above conditions are satisfied. Any phosphor and light-emitting element may be used as long as

For example, in the above embodiments, an LED chip was used as a specific example of the light-emitting element, but a semiconductor light-emitting element such as a semiconductor laser, or a solid-state light-emitting element such as an organic EL (Electro Luminescence) or an inorganic EL can be used as the light-emitting element. may be adopted. Further, for example, the illumination light source may include three or more types of phosphors having different center wavelengths of fluorescence. In either case, street luminaires can emit light that is perceived as bright in both peripheral and central vision, provided that the emission spectrum conditions described above are met.

Further, for example, in the above embodiments, the illumination light source realized as a light emitting module having an SMD structure has been described, but the illumination light source of the present disclosure is a so-called COB (Chip On Module) in which an LED chip is directly mounted on a substrate. Board) structure LED module may be used.

Further, the illumination light source of the present disclosure may be implemented as a remote phosphor type light emitting module in which a resin member containing phosphor is arranged at a position separated from the LED chip.

Further, the street lighting fixture of the present disclosure may be realized as remote phosphor type lighting in which a resin member containing phosphor is arranged at a position separate from the LED chip.

Further, the shape, structure, and size of the street lighting fixture of the present disclosure are not particularly limited, and the street lighting fixture of the present disclosure satisfies the emission spectrum conditions described in the above embodiment. should be filled.

In addition, forms obtained by applying various modifications to each embodiment that a person skilled in the art can think of, or realized by arbitrarily combining the components and functions of each embodiment within the scope of the present disclosure. Also included in the present disclosure is the form of

REFERENCE SIGNS LIST 100 Street Lighting Equipment 200 Street 300 Light Emitting Part 310, 310a Light Source for Illumination 313 LED Chip (Light Emitting Element)
317a green phosphor (phosphor)
317b red phosphor (phosphor)
LA irradiation surface

Claims (7)

A light-emitting unit that is arranged at a height of 2 m or more and 5 m or less from the road surface of the street and irradiates the street with white light,
The white light is
The correlated color temperature is 5000K or more and 6500K or less,
The color deviation is -10 or more and +10 or less,
The S/P ratio, which is the ratio of the luminous flux in scotopic vision and the luminous flux in photopic vision, is 2.0 or more,
The average horizontal illuminance on the irradiation surface on the street irradiated with the white light is 1 lx or more,
The emission spectrum of the white light is
Lumen equivalent is 300 lm / W or more,
having an emission peak in the wavelength range of 430 nm or more and 460 nm or less,
In the emission spectrum,
The ratio of the light intensity at a wavelength of 510 nm to the light intensity at the emission peak is 0.45 or more,
The ratio of the light intensity at a wavelength of 580 nm to the light intensity at the emission peak is 0.60 or more,
A street lighting fixture, wherein the ratio of light intensity at a wavelength of 650 nm to light intensity at a wavelength of 580 nm is 0.45 or more and 0.5 or less. The street lighting fixture according to claim 1, wherein the white light has a general color rendering index of 80 or more. The light emitting unit includes a light source for illumination,
The illumination light source is
a light emitting element;
a plurality of phosphors that are excited by the light from the light emitting element and emit light of a wavelength different from that of the light from the light emitting element,
The street lighting fixture according to claim 1 or 2, wherein the light emitting element has an emission peak in a wavelength range of 430 nm or more and 460 nm or less. The street lighting fixture according to claim 3, wherein the plurality of phosphors include a _Lu3Al5O12 :Ce3 ⁺ phosphor having an emission peak in _a wavelength _range of 540 nm or more and 550 nm or less. The street lighting fixture according to claim 3 or 4, wherein the plurality of phosphors include (Sr, Ca) _AlSiN3 :Eu2 ⁺ phosphors having an emission peak in a wavelength range of 610 nm or more and 620 nm or less. The street lighting fixture according to any one of claims 1 to 5, wherein a luminous flux of the white light emitted upward from the street lighting fixture is 5% or less of a total luminous flux of the white light. The street lighting fixture according to any one of claims 1 to 6, wherein the white light has a luminance value of 20000 cd/m ² or less at a vertical angle of 85 degrees or more.

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